High K diets strongly protect against stroke death and renal lesions. They also greatly reduce artery hypertrophy and prevent hypertensive injury to endothelial cells and cholesterol deposition. High K diets markedly reduce Na concentration in the papilla and markedly increase secretion by renal papillary interstitial cells. Such secretions act as powerful vasodilators and vasodilators usually oppose growth of vascular smooth muscle cells. We will test the hypothesis that high K diets exert their protective effect by stimulating the secretion of the renal interstitial cells. In a hypertensive setting, high NaCl diets can cause excessive mortality from cerebrovascular disease even though the high NaCl diet does not increase blood pressure at all. Does this effect of high NaCl extend to other arteries? We will test whether or not such high NaCl diets reduce EDRF release, increase cholesterol ester deposition, increase lipid peroxidation and raise macrophage adherence in the aorta, even when blood pressure is not altered. We will test whether a high K diet will reduce the high mortality rate in NaCl-fed Dahl R rats with post-DOCA hypertension. High NaCl diets increase Na concentration in the renal papilla by 24%. This could reduce the hormonal secretion of papillary interstitial cells. We will test the hypothesis that part of the high mortality of NaCl-fed Dahl R rats is due to reduced interstitial cell secretion.